Please help to explain me in detail about SAP Sybase ASE architecture
Please help to explain me the concepts that are listed below in a detailed manner,
a) Architecture of SAP Sybase ASE
b)About internal threads and their functionalities
d)Also how does ASE executes an SQL or update statement?
NOTE: I am a beginner and looking forward for your valuable response.
Rajesh Neemkar replied
Any RDBMS contains three important components
1. Storage..think about disk or your database or files (A file can be an image or video or a pdf etc.,)
2. Memory.. Allocated RAM to your RDBMS..think about fast response times. more memory = faster response times.
Note: Disks IOs are slower when compared to Memory IOs
3. Some processes running in the background...These are mandatory for your server to run and are called as ASE internal threads (known as Background processes in Oracle)
Others include..executable files like ASE RUN server file, Errorlog file, Interface file and Configuration file.
1. Your storage in Sybase is Databases;System databases (master, model, tempdb, sybsystemprocs, sybmgmtdb and saptools and saptempdb for SAP Applications) and User databases
2. Shared Memory is the technical term we use in ASE to indicate your memory which again is divided into 3 major components
- Procedure Cache: This is the place where compiled programs (called stored procedures for faster response times) are stored along with SQL statements abstract plans (in statement cache) to reduce the query optimization time
- Data cache: This is the place where the user (client process) gets his requested data actually from (Logical IO). If the requested data is not found in data cache, ASE fetches it from Disks (This is called Physical IO and is much slower than logical IO)
- Log cache: I would say the bread and butter for any Sybase DBA. It stores the information about the changes made to the user data. Known as Transaction log or syslogs (actually a table). This can be viewed as a big REDO log and UNDO segment combined in Oracle. Purpose of having Log cache is RECOVERY.
About ASE Architecture: ASE's threaded kernal uses its own threading model rather than depending on Operating system.
i.e., Instead of relying on the operating system (Unlike Oracle which creates a UNIX processes for every background process) to schedule operation on a CPU or multiple CPUs, ASE takes this responsibility for itself and handles scheduling and dispatching of user threads. This makes SAP SYBASE different from other RDBMS.
More details.. I will type when I find free time.
Note:This is NOT complete or exact but should serve your purpose "I will be very much great if you guys elucidate the concepts in a Lehman terminology. As,I am in learning stage, trying to understand the basic concepts first in an easy way ".
Dear Experts, You can correct me if my understandings are wrong.